[Tarto]

You don't need to hire a personal trainer if you just want to know how to use the machines. Machines are designed to be easy to use and minimize the risk of injury (on the other hand, most of them only allow to do isolation exercises). Most of them are pretty self-explanatory, if you're unsure you can look up on Internet.

If you've never worked out before, you should start with low weights to properly learn the movements. As long as you avoid jerky motions and control both the positive and negative phases (unlike many people do), you shouldn't have any problem.

If you need a full program, you can pay for a personal trainer...or you can save money and learn by reading books, looking up on Internet, asking questions on dedicated forums etc. It will take time to sort good information from bullshit, but you will learn a lot in the process (free weights vs machines, frequency of training, choice of exercises etc...). If you choose to do so, you should also learn about nutrition.

Think about it: do you prefer to follow instructions without understanding them, or know what you're doing and why you're doing it? There's no right answer, it just depends on your goals, motivation etc.